**12. Differential diagnosis of Capgras syndrome**

The differential diagnosis of patients who suffered CS is crucial. It is substantial to rule out the presence of brain disease in every patient with Capgras delusion [45]. Many patients with CS also present with medical illnesses of organic etiologies, associated with delusional misidentification; these patients may respond well to treatment of the medical condition underlying the onset of CS [47]. The syndrome should be differentiated from the quite common false recognitions which occur in confusional states and the transient misidentifications encountered in mania [8]. For this purpose, ending with a complete mental status examination, as well as thorough testing of cognition, is important. Neuropsychological testing and neuroimaging are often indicated. Clinicians should clarify the nature of the underlying psychiatric illness [45].
